Proposal: Adding json logging

I find it difficult to properly parse postgres logs into some kind of log aggregator (I use fluent bit). My two standard option are standard and csvlog.

I have reviewed some log samples and all DO contain some kind of multi line logs which are very uncomfortable to parse reliably in a log streamer.

I asked Michael Paquier about his solution: https://github.com/michaelpq/pg_plugins/tree/master/jsonlog

He was suggestion to take action and propose this extension again to be included in contrib:

https://github.com/michaelpq/pg_plugins/issues/24 

He mentioned the argument was rised of taking too much place.

This is true under the paradigm that logs are consumed by TTY or grep, however, if those logs are to be stored in a logging solution, this is not really of concern.

Please let me know if you need more context on my use case.

That beeing said the proposal is to accept this library into postgres contrib.

Please let me know, if I should prepare a patch.

David A.